Optical information storage media are widely used to record data such as audio, image, graphics data, and the like. Examples of optical information storage media include compact discs (CDs), digital versatile discs (DVDs), high definition (HD)-DVDs, Blue-ray discs (BDs), etc.
A variety of types of data can be stored in such an optical information storage media. However, data stored in optical information storage media may need to be destroyed or prevented from being reproducible upon a user request. For example, confidential data such as financial data, accounts data, privileged information, and the like may be stored in an optical information storage medium and but may also need to be destroyed so that no one can reproduce the data again.
As an illustration, in a conventional magnetic information storage device such as a hard disc drive, a strong external magnetic field may be placed close to a portion of the disc having data recorded thereon, so that original magnetic patterns written on that portion of the disc are changed into other patterns or are degaussed. Accordingly, data stored in the portion of the disc cannot be reproduced again.
However, to destroy data or prevent the data stored in an optical information storage medium from reproduced again, a method of breaking the optical information storage medium using a shredder or a method of scratching the surface of the optical information storage medium using a sharp probe have been suggested. In these conventional methods, additional breaking or scratching equipment is needed. Moreover, such methods may result in pulverized powders of the optical information storage medium, or a user may be hurt by a sharp portion of a piece from among pieces resulting from shredding or breaking of the optical information storage medium.
As another method, a method of introducing a malfunction with respect to reproducibility of original data recorded on an optical information storage medium by overwriting another data of discretionary patterns on the original data has been suggested. In such a method, reproducibility of data stored on an optical information storage medium becomes erroneous and additional breaking equipment is not needed. However, in such a method, a recording track is followed in order to overwrite the discretionary information. As such, when a problem occurs in relation to a tracking servo, data cannot be erased properly, and even if a normal tracking servo operation can be performed, it takes much time to erase the data. For example, in a DVD recordable (DVD-R) disc having an 18× speed, it takes about 6 minutes to erase the original data by overwriting discretionary information on the original data.